Telephone-repeater.



F. J. SHUBERT. TELEPHONE REPEATEB.

APPLICATION FILED JAN. 21, 1011.

IAKHYE autumn WITNESSES: I EN R .fifiw' By A TTORNE Y FRANK JOSEPHSHUIBERT, 0F PORTLAND, OREGON.

TELEPHONE-REPEATER.

Application filed January 27, 1911., Serial No. 605,032.

the art, at an intermediate point between the sections of a lineconnecting two telephone stations; and the association of these relayswith the line circuits in such way that the incoming and enfeebled voicecurrents from the transmitting station will be instrumental in theproduction of other voice currents similar in wave form but greatlystrengthened in volume, which larger-voice currents will go forth fromthe intermediate or relay station to the receiving station.

It has been found in the practice of the telephone repeater art that aditiiculty arises when the'attempt is made to make the repeater systemtransmit alternately in opposite directions, as is necessary in ordinarytelephonic conversation. This ditliculty manifests itself as a result ofmutual interference between the receiving and transmitting elements ofthe repeater system. The strengthened currents passing from the repeaterstation on the receiving section of the line will affect the receivingelement of the relay associated with that line section, in the same waythat incoming currents over that section would affect this receivingelement; and this, in turn, through the action of the correspondingtransmitting element of the relay, will affect the receiving ele ment ofthe relay of the. other line section. This again, through its associatedtransmitter element, will react'on the receiving element of thefirstmientioned line section, producing an endless chain ofdisturbances, and resulting in a phenomenon which is sometimes calledhowling.

It is a particular object of my present invention to so arrange thecircuits and parts of my repeater system as to eliminate thisdifficulty, and to this end I make such pro-' visionthat the respectivereceiving elements of the relays of each of the line sections at therepeater station will be affected only by the incoming voice currents ofits corresponding line section, and will be wholly unresponsive to anyoutgoing or relayed currents over its section of the line. I accomplishthis by employing at the repeating station a pair of artificial lines,each having approximately 1 the same electrical characteristics as thecorresponding section of the telephone line: and so associating theseartificial lines with the circuits and apparatus of the repeater systemthat incoming currents over one of the line sectionswill have completeinductive association with the electromagnetic element of thecorresponding relay; but so that the relayed currents from thetransmitting element of one of the telephone relays Wlll pass out overthe proper line section and the corresponding artificial line in suchway as to affect inductive neutrality with respect to the receivingelement of the relay corresponding to that line section.

A further and important object of my invention is to afford ready meansfor balancing the electrical characteristics of the artificial line withthose of the corresponding line section, this means comprising asuitable source of varying current for test purposes, together with aconvenient arrangement of switches and test apparatus, as will be morefully described hereinafter.

The drawing which accompanies this specification contains but a singlefigure, which is a diagrammatic representation of the circuits andapparatus at the repeater station connecting the two sections of thetelephone line. It is to be understood that the apparatus represented bythis drawing is subject to wide variation, the drawing purporting torepresent only the general types of apparatus to be employed rather thanthe specific details, after a manner that is well understood in circuitdiagrams relating to the telephone art.

Referring to the drawing, the repeating station ends of the two sectionsof the line.

are indicated at 2 and 21. Associated with each of these line sectionsare two induction coils and 7 for-the line section 2, and 20 and 16 forthe line section 21, the purposes of which I shall presently make clear.

The telephone relays employed in connection with my system may be of anyof they well known types, consisting" of an electromagnetic receivingelement and a variable resistance transmitting element, the latterSpecificatibn of Letters Patent. Patented June 18, 1912,

being placed under the-influence of the former through the medium of asoft iron armaof a carbon transmitter button similar to that of the wellknown solid back transmitter. The stationary element of this button isindicated at 25. Similarly, the repeater relay associated with the linesection 2 consists of an electromagnet 10 and the variable resistanceelement 11 12. The electromagnet 10 is adapted to receive impulses fromthe line section 2 through the inductive in fluence of the coil 4. Thevariable resistance element of this relay comprises the armature andmovable electrode 11 and the stationary electrode 12. The production ofthese relays, which are indicated diagram matically merely as atelephone receiver associated-with a telephone transmitter, forms no artof my invention, and I desire it to be .oistinctly understood that myinvention contemplates the use of any form of relay elements which arecapable of receiving a small or feeble current, and through the actionof this current, producing in another circuit a larger and strongercurrent of similar wave form.

In the lower portion of my drawing I show diagrammatically twoartificial lines associated with the line sections 2 and 21,respectively. The artificial line associated with the line section 21,as shown at 22, consists of a variable noninductive resistance 28, avariable inductive resistance 40, and a variable capacity 30. Theswitching arrangements shown for varying any of these at will areobvious, and these maybe of any well known type. The artificial line 8,corresponding to the line section 2, consists of variable non-inductiveresistance 27, a variable inductive resistance 41, and a variablecapacity 29. These artificial lines shall have a possible range ofresistance, inductance and capacity wide enough to cover the possiblerange of the corresponding characteristics of the line sections withwhich they are associated.

The receivers 33 and 34 are adapted to be associated ,with the secondarycoils 9' and 23 of the induction. coils 4 and 20, by means of theswitches 35 and 36, respectively; ,the operation of these switchesserving at the same time to cut off the corresponding receiving elements10 and 24 of the telephone relays. In like manner the switches 37 and 38may be actuated to cut off the normal connection between the secondarywindings .15 and 26 of the induction coils 16 and 7 from theircorresponding relay transmitter elements, and, when so operated, toconnect these secondary windings with the circuit 39, which is connectedwith a source of high frequency alternating current. capable of givingas close approximation as may be desired in frequency and volume tovoice currents. These receivers 33 and 34 and switches 35, 36, 37 and 38play no part in the ordinary normal operation of the repeating system,and it is'convenient. in securing an understanding ofthe normaloperation of my system to ignore these two receivers and to rememberthat the inductioncoil windings 9 and 23 are connected directly to theterminals of the receiving magnets 10 and 24, and that the inductioncoil windings l5 and 26 are connected directly in the local circuits of.the transmitting relay elements 12 and 25.

these incoming currents will pass through the windings 31- and 3 of theinduction coil 4 in series, and throu h the artificial line 8 as a pathfrom one slde of the line to the other. In other words, if the flow becon-j sidered as from the upper to the lower side of the line 2, thecurrents will divide at the point 5, one portion flowing through :thesecondary winding 6 ot the induction coil 7 and the other portionflowing through the winding 3 and the artificial line. The effects ofthese two components of the current flowing in the same directionthrough the coils 31 and 3 of the induction coil 4 Wlll be cumulativewith respect to the secondary winding 9 of that coil, and the inducedcurrents in that coil willflow through the receiving magnet 10 of therelay associated with the line 2. The varying flow of current throughthe receiving magnet 10 will cause corredepended upon to aflect thereceiver at the distant end of the line 21. Since the secondary coil 17taps the inductive center of the line winding of the coil 20, and sincethe artificial line '22 is assumed to present the winding 32 over thereal line 21 to the dis tant instrument, and the other portion will fiowthrough the winding 19 over the artificial line'22. Since these twoportions of the current are alike in volume, form and phase, and sincethey flow in opposite directions through the two similar coils l9 and32, it follows that their inductive influence on the winding 23 will beml, and therefore that they will produce no effect upon the receivingmagnet 24 of the relay associated with the line 21. Since the entirearrangement is symmetrical with respect to the two lines, it followsthat any currents received over the line 21 will produce similar butstronger currents in line 2 without any retroactive effect upon thereceiving .magnet 10 of that line. 1 v

It will be seen that I accomplish the transmission through the repeaterdevice in either direction in such manner that relayed or strengthenedcurrents will not affect the receiving magnet of the relay associatedwith the receiving section of the line. I do this by causing a divisionof both incoming and outgoing currents, and so associating each relayreceiving magnet with its section of the line, that the two parts ordivisions of any incoming currents to the repeating' station over thatsection will act upon the relay receiving magnet cumula- I tively;whilethe two divisions of any outgoing current from. the repeatingstation over that section will be equal, and will act on the relayreceiving magnet difierentially. In the particular arrangement which Ishow, this result is accomplished by connecting the coils 6 and 17 tothe center point-s of the line windings of the coils 20 and 4, and asthe coils 6 and 17 are the ones which receive the induced currents fromthe local circuits of the relays, it follows, owing to the fact that thecharacteristics of the artificial lines are the same as those of thereal lines, that the relayed currents through the two halves of the linewinding-of the coils 20 and 4, respectively, will be always equal and inopposite directions. It is clear, however, that the two windings 3 and31 of the coil i, or 19 and 32 of the coil 20, need not necessarily bemade equal, as any in equality between the two windings of one of thesepairs may be compensated for by a proportional adjustment of theresistance and other characteristics of the corresponding artificialline with respect to its line section.

In order to provide for the convenient adjustment of the artificiallines to make them as nearly as possible bear the proper relations, intheir electrical characteristics, to the'correspondiug real lines, Iprovide the keys 36, 37, 33, the receivers 33 and 34, and the highfrequency alternating current circuit 39. The generator connected withthis circuit 39 maybe-one of alternating currents having a frequenjcyapproximating that of the average frequency of vibration of the humanvoice, or it may be a generator of voice currents, such as an ordinarytelephone transmitter. Assuming that it is desired to adjust theartificial line 8 to be as nearly as possible like the real line 2, thekey 35 should be operated, thus'disconnecting relay magnet 10 andconnecting the receiver 33 in its place in the circuit of -the inductioncoil winding 9. At the same time the key 38 should be thrown, thusdisconnecting the coil 26 from the local circuit which includes thevariable resistance '25 42-, and at the same-time connecting this coil26 with the generator circuit 39. Under these conditions current fromthe generator circuit 39 will pass through the winding 26 v and willcause induced currents .to pass through the corresponding winding 6.These currents will divide at the point 5 between the real line 2 andthe artificial line 8. When the artificial line has been made in allelectrical respects like the real line, the current flowing throughthetwo will be equal, and as these pass in opposite direction throughthe windings 3 and 31, their combined eiiects upon the coil 9 will beTherefore, silence in the receiver 33 will indicate that the properadjustment of the artificial line 8 has been attained for the existingconditions on the real line "2. The

sameexplanation with respect to the keys 36 22 with the, real line 21may be determined or secured.

Having thus described my invention, what I claim as new and desire"tosecure by United States Letters Patent is:

1. In a telephone repeater system, a telephone line divided into twosections; a telephone relay, an induction coil having one winding in oneof said line sections and its other Winding in a localcircuit includingthe receiving magnet of said relay, whereby said relay may receiveenergy from said sectionof the line; an artificial line associated .Withthe other section of said line, and

means for passing therelayed currents from said relay into said othersection and said artificial line in multiple.

multiple.

2. In a telephone repeater system, two sections of a telephone lineextending from a relay-station; a telephone relay; an induction coilhaving one winding connected to the receiving magnet of said relay andits other windin in one of said line sections; an artificial fineassociated with the other section of said line and having similarelectriczil characteristics; and means for passing the relayed currentsfrom said relay into said other section and said artificial line in 3.In a telephone repeater system, two sections of a tele hone line joinedat a relay station; a te ephone relay; an induction coil associatingsaid relay with one of said line sections; an artificial line associatedwith the other section of said line; means for passing the relayedcurrents from said relay into said other section and said artificialline in multiple; and a second relay havingits receiving coil associatedwith said other line section and said artificial line,

'whereby relayed currents from said first re-.

lay do not afi'ect the receiving element of saidsecond relay.

4. In a telephone repeater system, a telephone line divided into twosections; a telephone relay; an induction coil having one of itswindings connected in the circuit of one of said line' sections and itsother winding connected with the receiving magnet'of said relay; anartificial line associated with the other section of said line; a localcircuit for the transmitting element of said relay; a source of currentin said local circuit, and an induction coil having its primary in saidlocal circuit and its secondary in a common path in said artificial lineand said other section of said telephone line.

5. In a telephone repeater system, a telephone line divided into twosections; a telehone relay; an induction coil connected to inductivelytransmit energy from one of said line sections to the receiving magnetof said relay; an artificial line associated with the other section ofsaid line; a local circuit for the transmitting element of said relay; a

J source of current in said local circuit; an in- 'duction coil havingits primary in said local circuit and its secondary in a common path insaid artificial line and said other section of said telephone line; anda second relay having its receiving coil-diiferentiall associated withsaid other line section an said artificial line, whereby relayedcurrents from said first relay do'not afiect the receiving element ofsaid second relay.

6. In a telephone repeater system, a pair of line sections joined at arepeater station; a pair of tele hone relays, each capable of receivingfe b e currents from one line section and impressing augmented currentson the other line section; a pair of artificial lines, one for each linesection; an induction coil for each line section, each having itsprimary in the local circuit of the relay corresponding to the othersection and its secondary in a common path of its own line and thecorresponding artificial line; and a second induction coil for each linesection having one-half its'primary in its line section and one-half inthe corresponding artificial line, and its secondary connected with therelay magnet of that line section.

7. In a telephone repeater system, a pair of line sections terminatingin a relay station a pair of artificial lines; means for adjusting saidartificial lines to possess similar electrical characteristics to theirrespective line sections; means for impressing a periodically varyintest current on one of said line sections an its correspondingartificial line in multiple; and a telephone receiver adapted to beinductively, differentially associated with said line section andsaidartificial line for determining the roperadjustment of saidartificial line with respect to said line section.

8. In a repeater system, a telephone linedivided into two sections; an'artificial line for each line section; a source of test current; meansfor impressing said test current on each line section and itscorresponding artificial line; a test instrument adapted to bedifferentially associatedwith res ect to the test currents from saidsource owing through the line section and its artificial line; and meansfor adjusting the electrical characteristics of each artificial line toapproximate those of its line section.

9. In a repeater system, a telephone line divided into two sections; anartificial line for each line section; a source of test current; meansfor impressing said test current on either of said line sections and itscorresponding artificial line; a test instrument

